US5593936A - Hydrated niobium oxide and hydrated tantalum oxide catalysts, their preparation and a process for preparing N-alkylated anilines using these catalysts - Google Patents

Hydrated niobium oxide and hydrated tantalum oxide catalysts, their preparation and a process for preparing N-alkylated anilines using these catalysts Download PDF

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US5593936A
US5593936A US08/410,466 US41046695A US5593936A US 5593936 A US5593936 A US 5593936A US 41046695 A US41046695 A US 41046695A US 5593936 A US5593936 A US 5593936A
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hydrated
catalysts
catalyst
pores
oxide
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Volker Glock
Ursula Pentling
Bernd Pennemann
Joerg-Dietrich Jentsch
Eberhard Zirngiebl
Horst Koller
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Lanxess Deutschland GmbH
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Bayer AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/20—Vanadium, niobium or tantalum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/66—Pore distribution
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
    • C07C209/04—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups
    • C07C209/14—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups by substitution of hydroxy groups or of etherified or esterified hydroxy groups
    • C07C209/18—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups by substitution of hydroxy groups or of etherified or esterified hydroxy groups with formation of amino groups bound to carbon atoms of six-membered aromatic rings or from amines having nitrogen atoms bound to carbon atoms of six-membered aromatic rings

Definitions

  • the invention relates to hydrated niobium oxide and hydrated tantalum oxide catalysts having particular pores and lateral fracture harnesses, their preparation and a process for preparing N-alkylated anilines using these catalysts.
  • N-alkylated aromatic amines are starting materials for producing dyes, pesticides, urethanes, drugs and crop protection agents. Furthermore, they are used as mineral oil additives and as additives for surface coatings and other polymer systems.
  • N-alkylated aromatic amines can be prepared by reacting aromatic amines with alkanols or dialkyl ethers in the gas phase over heterogeneous catalysts.
  • the catalyst can be applied to a support or provided with a binder and granulated or extruded. It can also be provided with a lubricant and converted into a pellet form by tabletting.
  • the granulated catalyst has sufficient strength. It is known that catalysts having insufficient strength can disintegrate because of their own weight, pressure loss in the reactor, thermal stressing and other causes, which can then lead to very non-uniform pressure losses in fixed beds and finally to blocking of the reactor. Catalysts having low strength therefore have only a short lifetime and are not suitable for industrial use.
  • a measure of the strength is the so-called lateral fracture hardness. The determination of the lateral fracture hardness can be carried out using conventional measuring instruments, e.g. using those supplied commercially by Schleuniger.
  • Catalysts having fracture hardnesses below 20N are unsuitable for industrial use, since experience has shown that they do not withstand the stresses occurring during charging and operation of an industrial reactor (see Comparative Example 2). It is known that the activity of a mechanically shaped catalyst and its strength are inversely proportional and that usually an increase in the strength causes a decrease in the catalytic activity.
  • Hydrated niobium oxide and hydrated tantalum oxide catalysts have now been found, which catalysts contain pores having diameters in the range from 0.4 to 10,000 nm and are characterized in that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm makes up at least 30% of the total pore volume of the catalyst. Preferably, the proportion of these pores is at least 33% of the total pore volume and particularly preferably at least 36%.
  • Catalysts of the invention generally have lateral fracture hardnesses of over 20N, preferably over 25N.
  • the pore volume and the pore diameter distribution can be determined in a known manner, for example using a mercury porosimeter.
  • Catalysts of the invention can be prepared by mixing hydrated niobiumoxide or hydrated tantalum oxide with an inert solid, for example graphite, and converting such mixtures into solid pellet form, e.g. by tabletting using a tabletting press.
  • an inert solid for example graphite
  • routine trials can be carried out beforehand, in which pressures can be varied, for example, in the range from 500 to 50,000 kg/cm 2 and account should be taken of the fact that the application of higher pressures lowers the proportion of pores having diameters in the range from 100 to 1000 nm.
  • the hydrated niobium oxide and hydrated tantalum oxide catalysts thus obtained have the lateral fracture hardness required for industrial use and at the same time have a significantly higher activity than catalyst shown hitherto.
  • the catalysts of the invention can be used, for example, for dehydrogenations, oxidative dehydrogenations, ammonoxidations, polymerizations, isomerizations, decompositions (for example of NO x ), Fischer-Tropsch syntheses, hydrogenations and alkylations, in particular N-alkylations.
  • catalysts of the invention are particularly suitable for the preparation of N-alkylanilines from anilines and alkanols.
  • this process can be carried out using anilines of the formula (I) ##STR1## where R 1 and R 2 are, independently of one another, hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, fluorine, chlorine, bromine or cyano and
  • R 3 is hydrogen, C 1 -C 12 -alkyl or C 3 -C 7 -cycloalkyl
  • R 4 is C 1 -C 12 -alkyl or C 3 -C 7 -cycloalkyl
  • This reaction can be carried out in the liquid phase or in the gas phase, for example at temperatures of from 160° to 400° C. and at molar ratios of alkanol to anilines of from 0.5 to 10:1.
  • the above-described process for preparing N-alkylanilines has the surprising advantage that it permits the achievement of high space-time yields and the amounts of unreacted starting materials can be kept small.
  • the catalyst used has sufficient strength for a process to be carried out in industry.
  • a stainless steel reaction tube having an internal diameter of 25 mm was charged with 118.5 g of tabletted hydrated niobiumoxide (diameter 6.4 nm) in which 24% of the total pore volume was made up by the pores having a diameter of from 100 to 1000 nm and which had a mean lateral fracture hardness of 148N.
  • a gas mixture of ethanol and unsubstituted aniline in a molar ratio of 1:4 was passed at 261° C. through this catalyst bed at a rate of 1.35 g/ml h.
  • the reaction product formed over the course of 48 hours had the following composition according to gas chromatography:
  • Hydrated niobiumoxide was, with the addition of 3.5% of graphite, pressed in a laboratory press to form tablets which have a diameter of 5 mm, a mean lateral fracture hardness of 14N and in which 56% of the total pore volume is made up by pores having a diameter of from 100 to 1000 nm.
  • 89 g of this catalyst were tested under the conditions of Comparative Example 1, but at a temperature of 265° C., and after 168 hours a reaction mixture having the following composition was obtained:
  • Hydrated niobium oxide was, with the addition of 4% of graphite, pressed to form tablets on an industrial press in such a way that the tablets have a diameter of 5 mm, a mean lateral fracture hardness of 41N and 42% of the total pore volume is made up of pores having a diameter of from 100 to 1000 nm. 106.3 g of the catalyst were tested under the conditions of Comparative Example 1. This gave a reaction mixture having the following composition:

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Catalysts (AREA)

Abstract

New hydrated niobium oxide and hydrated tantalum oxide catalysts containing pores having diameters in the range from 0.4 to 10,000 nm are characterized in that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm is at least 30% of the total pore volume of the catalyst. The catalysts can be prepared by mixing hydrated niobium oxide or hydrated tantalum oxide with an inert solid and converting this mixture into a solid pellet form, with the pressure in the apparatus for preparing catalysts in pellet form being set in such a way that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm is at least 30% of the total pore volume of the catalyst. Such catalysts are particularly suitable for preparing N-alkylanilines from anilines and alkanols.

Description

The invention relates to hydrated niobium oxide and hydrated tantalum oxide catalysts having particular pores and lateral fracture harnesses, their preparation and a process for preparing N-alkylated anilines using these catalysts.
N-alkylated aromatic amines are starting materials for producing dyes, pesticides, urethanes, drugs and crop protection agents. Furthermore, they are used as mineral oil additives and as additives for surface coatings and other polymer systems.
Various methods are known for preparing secondary and tertiary aromatic amines. Thus, it is already known that N-alkylated aromatic amines can be prepared by reacting aromatic amines with alkanols or dialkyl ethers in the gas phase over heterogeneous catalysts.
The prior art for preparing N-alkylated anilines over heterogeneous catalysts is described, for example, in EP-A 433 811. This document also describes the use of hydrated niobium oxide and hydrated tantalum oxide as catalyst.
To prepare granulated materials, extrudates or spheres, the catalyst can be applied to a support or provided with a binder and granulated or extruded. It can also be provided with a lubricant and converted into a pellet form by tabletting.
For use of the catalyst in a fixed-bed gas-phase reactor, it is important that the granulated catalyst has sufficient strength. It is known that catalysts having insufficient strength can disintegrate because of their own weight, pressure loss in the reactor, thermal stressing and other causes, which can then lead to very non-uniform pressure losses in fixed beds and finally to blocking of the reactor. Catalysts having low strength therefore have only a short lifetime and are not suitable for industrial use. A measure of the strength is the so-called lateral fracture hardness. The determination of the lateral fracture hardness can be carried out using conventional measuring instruments, e.g. using those supplied commercially by Schleuniger.
Catalysts having fracture hardnesses below 20N are unsuitable for industrial use, since experience has shown that they do not withstand the stresses occurring during charging and operation of an industrial reactor (see Comparative Example 2). It is known that the activity of a mechanically shaped catalyst and its strength are inversely proportional and that usually an increase in the strength causes a decrease in the catalytic activity.
Hydrated niobium oxide and hydrated tantalum oxide catalysts have now been found, which catalysts contain pores having diameters in the range from 0.4 to 10,000 nm and are characterized in that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm makes up at least 30% of the total pore volume of the catalyst. Preferably, the proportion of these pores is at least 33% of the total pore volume and particularly preferably at least 36%.
Catalysts of the invention generally have lateral fracture hardnesses of over 20N, preferably over 25N.
The pore volume and the pore diameter distribution can be determined in a known manner, for example using a mercury porosimeter.
Catalysts of the invention can be prepared by mixing hydrated niobiumoxide or hydrated tantalum oxide with an inert solid, for example graphite, and converting such mixtures into solid pellet form, e.g. by tabletting using a tabletting press. To obtain catalysts in accordance with the invention, it is generally necessary to set the pressure in the apparatus for preparing catalysts in pellet form in such a way that the volume of the pores of the catalyst having a diameter of from 100 to 1000 nm is at least 30% of the total pore volume. To set a suitable pressure in the apparatus for preparing catalysts in pellet form, routine trials can be carried out beforehand, in which pressures can be varied, for example, in the range from 500 to 50,000 kg/cm2 and account should be taken of the fact that the application of higher pressures lowers the proportion of pores having diameters in the range from 100 to 1000 nm.
The hydrated niobium oxide and hydrated tantalum oxide catalysts thus obtained have the lateral fracture hardness required for industrial use and at the same time have a significantly higher activity than catalyst shown hitherto. The catalysts of the invention can be used, for example, for dehydrogenations, oxidative dehydrogenations, ammonoxidations, polymerizations, isomerizations, decompositions (for example of NOx), Fischer-Tropsch syntheses, hydrogenations and alkylations, in particular N-alkylations.
It has furthermore been found that catalysts of the invention are particularly suitable for the preparation of N-alkylanilines from anilines and alkanols. For example, this process can be carried out using anilines of the formula (I) ##STR1## where R1 and R2 are, independently of one another, hydrogen, C1 -C4 -alkyl, C1 -C4 -alkoxy, fluorine, chlorine, bromine or cyano and
R3 is hydrogen, C1 -C12 -alkyl or C3 -C7 -cycloalkyl
and alkanols of the formula
R.sup.4 --OH                                               (II),
where
R4 is C1 -C12 -alkyl or C3 -C7 -cycloalkyl
to obtain N-alkylanilines of the formula (III) ##STR2## where R1 to R4 are as specified above.
This reaction can be carried out in the liquid phase or in the gas phase, for example at temperatures of from 160° to 400° C. and at molar ratios of alkanol to anilines of from 0.5 to 10:1. The above-described process for preparing N-alkylanilines has the surprising advantage that it permits the achievement of high space-time yields and the amounts of unreacted starting materials can be kept small. The catalyst used has sufficient strength for a process to be carried out in industry.
The percentages given are, unless otherwise indicated, by weight.
EXAMPLES COMPARATIVE EXAMPLE 1
A stainless steel reaction tube having an internal diameter of 25 mm was charged with 118.5 g of tabletted hydrated niobiumoxide (diameter 6.4 nm) in which 24% of the total pore volume was made up by the pores having a diameter of from 100 to 1000 nm and which had a mean lateral fracture hardness of 148N. A gas mixture of ethanol and unsubstituted aniline in a molar ratio of 1:4 was passed at 261° C. through this catalyst bed at a rate of 1.35 g/ml h. The reaction product formed over the course of 48 hours had the following composition according to gas chromatography:
Aniline: 17.47% by area
N-ethylaniline: 32.51% by area
N,N-diethylaniline: 47.90% by area
Byproducts: 2.12% by area
COMPARATIVE EXAMPLE 2
Hydrated niobiumoxide was, with the addition of 3.5% of graphite, pressed in a laboratory press to form tablets which have a diameter of 5 mm, a mean lateral fracture hardness of 14N and in which 56% of the total pore volume is made up by pores having a diameter of from 100 to 1000 nm. 89 g of this catalyst were tested under the conditions of Comparative Example 1, but at a temperature of 265° C., and after 168 hours a reaction mixture having the following composition was obtained:
Aniline: 8.22% by area
N-ethylaniline: 39.09% by area
N,N-diethylaniline: 51.12% by area
Byproducts: 1.57% by area
The strength of this catalyst was not sufficient for industrial use since even at a height of the fixed bed of 3 m it broke under its own weight.
EXAMPLE 1
Hydrated niobium oxide was, with the addition of 4% of graphite, pressed to form tablets on an industrial press in such a way that the tablets have a diameter of 5 mm, a mean lateral fracture hardness of 41N and 42% of the total pore volume is made up of pores having a diameter of from 100 to 1000 nm. 106.3 g of the catalyst were tested under the conditions of Comparative Example 1. This gave a reaction mixture having the following composition:
Aniline: 7.23% by area
N-ethylaniline: 35.05% by area
N,N-diethylaniline: 55.66% by area
Byproducts: 2.06% by area
In contrast to Comparative Example 2, this catalyst had sufficient strength for industrial use, since it did not break under its own weight at a fixed bed height of 3 m.
EXAMPLE 2
597 kg of the catalyst from Example 1 were charged into a tube-bundle reactor comprising 350 tubes having a diameter of 2.5 cm each and a length of 3.5 m. A mixture of ethanol and aniline in a molar ratio of 1:3 was passed at 262° C. over the catalyst bed at a rate of 600 kg/h. The reaction product formed over the course of 24 hours had the following composition according to gas chromatography:
Aniline: 4.23% by area
N-ethylaniline: 38.81% by area
N,N-diethylaniline: 53.99% by area
Byproducts: 2.97% by area
After 500 hours, the catalyst still displayed no significant mechanical defects.

Claims (4)

What is claimed is:
1. A catalyst comprising at least one oxide selected from the group consisting of hydrated niobium oxide and hydrated tantalum oxide, having pores with diameters in the range from 0.4 to 10,000 nm, in which catalyst the volume of pores having a diameter of from 100 to 1,000 nm makes up at least 30% of the total pore volume of the catalyst, the catalyst having a lateral fracture hardness of over 20N.
2. A catalyst according to claim 1, wherein the volume of the pores having a diameter of from 100 to 1,000 nm make up at least 33% of the total pore volume.
3. A process for preparing a catalyst comprising at least one oxide selected from the group consisting of hydrated niobium oxide and hydrated tantalum oxide, having pores with diameters in the range from 0.4 to 10,000 nm, which process comprises mixing at least one oxide selected from the group consisting of hydrated niobium oxide and hydrated tantalum oxide with an inert solid, and pressing the mixture to convert it into pellets in such a way that the volume of the pores having a diameter of from 100 to 1,000 nm makes up at least 30% of the total pore volume of the finished catalyst.
4. A catalyst according to claim 1, in the form of tablets of approximately 5 mm in diameter.
US08/410,466 1994-03-31 1995-03-24 Hydrated niobium oxide and hydrated tantalum oxide catalysts, their preparation and a process for preparing N-alkylated anilines using these catalysts Expired - Fee Related US5593936A (en)

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DE4411234.3 1994-03-31
DE4411234A DE4411234A1 (en) 1994-03-31 1994-03-31 Niobium oxide hydrate and tantalum oxide hydrate catalysts, their preparation and a process for the preparation of N-alkylated anilines with these catalysts

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8629080B2 (en) 2011-03-21 2014-01-14 Saudi Arabian Oil Company Hydrated niobium oxide nanoparticle containing catalysts for olefin hydration
US10618042B1 (en) 2017-05-31 2020-04-14 University Of South Florida Mixed metal oxide extrudate catalyst

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135145A2 (en) * 1983-08-17 1985-03-27 CBMM Internacional Ltda. Solid acid catalysts and process of producing the same
US4973569A (en) * 1988-11-01 1990-11-27 The Dow Chemical Company Preparation of group VB metal phosphate catalysts therefor
EP0433811A2 (en) * 1989-12-21 1991-06-26 Bayer Ag Process for preparing N-alkylated aromatic amines
EP0509493A1 (en) * 1991-04-17 1992-10-21 Mitsubishi Chemical Corporation Method for producing a lactam

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135145A2 (en) * 1983-08-17 1985-03-27 CBMM Internacional Ltda. Solid acid catalysts and process of producing the same
US4973569A (en) * 1988-11-01 1990-11-27 The Dow Chemical Company Preparation of group VB metal phosphate catalysts therefor
EP0433811A2 (en) * 1989-12-21 1991-06-26 Bayer Ag Process for preparing N-alkylated aromatic amines
US5166440A (en) * 1989-12-21 1992-11-24 Bayer Aktiengesellschaft Process for the preparation of n-alkylated aromatic amines
EP0509493A1 (en) * 1991-04-17 1992-10-21 Mitsubishi Chemical Corporation Method for producing a lactam

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8629080B2 (en) 2011-03-21 2014-01-14 Saudi Arabian Oil Company Hydrated niobium oxide nanoparticle containing catalysts for olefin hydration
US10618042B1 (en) 2017-05-31 2020-04-14 University Of South Florida Mixed metal oxide extrudate catalyst

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DE59503564D1 (en) 1998-10-22
EP0674943A1 (en) 1995-10-04
EP0674943B1 (en) 1998-09-16
DE4411234A1 (en) 1995-10-05
JPH07289893A (en) 1995-11-07
ES2120646T3 (en) 1998-11-01

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